Steering and reversing system for a marine jet propulsion unit

ABSTRACT

A steering and reversing system for a marine jet propulsion unit having a stationary nozzle (3) for discharging a water jet rearwardly from the unit comprises a pair of steering and reversing members (4, 5) which are mounted side by side at the rear end of the nozzle and individually pivotable in opposite directions about upright axes (7) from a non-deflecting position to first and second deflecting positions. In the non-deflecting position, the steering and reversing members (4, 5) form a rearwardly directed extension of the nozzle, while in the first deflecting position each member diverts a portion of the water jet laterally outwardly by means of its front section (4a, 5a) and in the second deflecting position each member deflects a portion of the water jet downwardly and forwardly by means of scoop-like members at its rear section (4b, 5b).

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates to a steering and reversing system for a marinejet propulsion unit for a water craft.

Basically, a jet propulsion unit for a water craft comprises a pump,usually an axial-flow pump, supported in the craft, typically in thestern thereof, the inlet of which is connected with a water intake inthe bottom of the craft and the outlet of which is connected with arearwardly directed discharge tube or nozzle, usually projectingrearwardly beyond the transom of the craft, for discharging thecraft-propelling water jet.

For side steering of the craft, a mechanism is provided to deflect thewater jet, or at least a part of it, laterally in either direction, andfor slowing down the craft and/or making it go astern, a reversingmechanism is provided to deflect the water jet at least partially in theforward direction, usually downwardly and forwardly.

In the known water jet propulsion units, the side steering is usuallyaccomplished by pivoting the nozzle, or the rear part of it, about avertical axis by means of one or more actuators, commonly in the form ofhydraulic cylinders. The reversal of the thrust of the water jet usuallyis accomplished by a separate reversing mechanism which is mounted in orbehind the nozzle and comprises one or more flaps or scoop-like elementswhich are operable by means of one or more actuators, commonly hydrauliccylinders, to intercept the water jet and divert at least a portion ofit in the desired direction, usually downwardly and forwardly.

Known side-steering and reversing systems thus comprise a large numberof movable elements and actuators and therefore are complicated,space-consuming, heavy and expensive.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a steering andreversing system that is simpler, lighter, less space-consuming andcheaper than the known steering and reversing systems of theabove-described kind.

To this end, according to the invention, there is provided a steeringand reversing system for a jet propulsion unit for a water craft as setforth in the claims.

Generally stated, the steering and reversing system according to theinvention comprises two elongate steering and reversing members whichare mounted side by side on the nozzle and individually pivotable inopposite directions about upright axes from a neutral or non-deflectingposition, in which they permit the water jet to pass rearwardly withoutbeing obstructed, to a first deflecting position, in which a frontsection intercepts a portion of the water jet and deflects it laterallyoutwardly from the nozzle, and a second deflecting position, in which arear section including a scoop-like jet reversing element intercepts aportion of the water jet and deflects it downwardly and forwardly.

The invention is described in greater detail hereinafter with referenceto the accompanying drawings, in which an embodiment of the steering andreversing system according to the invention is shown by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a steering and reversing system embodyingthe invention, the system being shown in a passive or neutral positionfor propelling the water craft straight ahead;

FIG. 2 is a similar top plan view showing the system in a position forpropelling the water craft forwardly while turning;

FIG. 3 is a similar top plan view showing the system in a position forfull reversal for going straight astern;

FIG. 4 is a similar top plan view showing the system in a position forcausing the craft to go astern while turning;

FIG. 5 is a side view of one of the steering and reversing members ofthe steering and reversing system shown in FIGS. 1 to 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE INVENTION

Referring to the drawings, only the rearmost portion of a water jetpropulsion unit is shown, namely a pump housing 1 and a stationaryoutlet duct or nozzle 3 secured to a flange 2 of the pump housing andprovided with the steering and reversing system according to theinvention. Other parts of the jet propulsion units are omitted in theinterest of clarity, as they can be constructed in any suitable manner,e.g. as illustrated and described in U.S. Pat. No. 4,474,561 or U.S.Pat. No. 4,538,997. Naturally, the connection of the nozzle 3 to thepump housing 1 may be different from that which is illustrated. Forexample, the nozzle may be integral with the pump housing.

The nozzle 3 is of generally rectangular, e.g. square, cross-section andcomprises a horizontal top wall 3a, an essentially similar bottom wall(not shown), and two vertical side walls 3b and 3c. The two side walls3b, 3c do not extend rearwardly as far as to the rear end of the nozzle3, but have their rear edges at a considerable distance from that end.Accordingly, both sides of the rear portion of the nozzle 3 are open.

As shown in the drawings, the steering and reversing system comprisestwo elongate steering and reversing members 4 and 5 which are positionedsymmetrically side by side at the rear end of the nozzle 3 on oppositesides of a vertical center plane 6 containing the axis of the nozzle.The two steering and reversing members are shaped such that each of themis a mirror image of the other in the center plane 6 and are mounted onvertical pivots 7 and 8 supported by the top and bottom walls of thenozzle 3. The steering and reversing members 4 and 5 are individuallypivotally movable about the pivots 7 and 8 by means of respectiveactuators in the form of hydraulic double-acting cylinders 9 and 10; inthe interest of simplicity and clarity, these actuators are shown onlyin FIG. 1.

Each of the two steering and reversing members 4, 5, of which thesteering and reversing member 4 is also shown in side view in FIG. 5,comprises a front section 4a, 5a located forwardly of the associatedpivot 7 and 8 beneath the top wall 3a of the nozzle 3 and a rear section4b, 5b located rearwardly of the pivot 7 and 8.

A vertical side panel 11 on each member 4, 5 extends over both the frontsection and the rear section and forms an outer wall of each member.

A top panel 12 is secured (welded) to and extends inwardly from thehorizontal upper edge of the side panel 11, likewise over both the frontsection 4a, 5a and the rear section 4b, 5b. The top panel 12 ishorizontal and positioned immediately beneath the top wall 3a of thenozzle 3 at least in the region of the pivot 7.

As shown in FIGS. 1 to 4, the top panel 12 is tapered forwardly over thefront section 4a, 5a while it is rectangular over the rear section 4b,5b. At the transition between the front and rear sections, the inneredge of the top panel 12 is convexly curved about the pivot 7 andlocated in or very close to the vertical center plane 6.

As is also shown in FIGS. 1 to 4, each steering and reversing member 4,5 is bent about the associated pivot 7 and 8 such that the rear sections4b, 5b diverge rearwardly from the nozzle 3 when the steering andreversing members are in the neutral or non-deflecting position shown inFIG. 1, in which the front portion of the side panel 11 is aligned withthe associated side wall 3b, 3c of the nozzle 3, i.e. parallel with thevertical center plane 6.

As is best shown in FIG. 5, the top wall 12 is extended downwardly andforwardly so as to form a scoop-like member. This scoop-like memberserves to deflect a stream of water flowing rearwardly beneath the topwall such that the stream is caused to exit from the steering andreversing member 4, 5 downwardly and forwardly as indicated by arrows 13in FIG. 5.

As is also apparent from FIG. 5, each steering and reversing member 4, 5comprises a horizontal bottom panel 14 which is secured to and extendsinwardly from the horizontal lower edge of the side panel 11. The bottompanel 14 extends over the front section 4a, 5a of the steering andreversing member and a portion of the rear section 4b, 5b. From FIG. 5it is also seen that the top and bottom panels 12, 14 are provided withelements forming the pivot 7.

One or more guide vanes secured to the rear portion of the side panel 11of each steering and reversing member 4, 5 assist in the deflection andreversing of the water jet in the scoop-like member. One such guide vaneis shown at 15 in FIG. 5.

In the neutral or non-deflecting position shown in FIG. 1, the frontportions of the side panels 11 form extensions of the side walls 3b, 3cof the nozzle 3 and cover the lateral openings of the nozzle which aredefined by the top wall 3a and the bottom wall. In this position, thescoop-like jet reversing members of the rear sections 4b, 5b arepositioned outside the area directly behind the jet discharge passagedefined by the nozzle 3, that is, outside the area swept by the waterjet discharged from the nozzle. In other words, the steering andreversing members 4, 5 do not influence the water jet which is thusdirected straight rearwardly as indicated by arrows 16 in FIG. 1 topropel the water craft straight ahead.

If one of the steering and reversing members, e.g. the steering andreversing member 4, is swung such that its front section is movedinwardly into the discharge passage of the nozzle 3 as shown in FIG. 2,it assumes a first jet deflecting position to deflect a portion of thewater jet laterally outwardly away from the nozzle 3 as is indicated byarrows 17 in FIG. 2. In this position, the outer side of the side panel11 of the steering and reversing member 4 forms a smooth, curveddeflecting surface. The remaining portion of the water jet is stilldirected straight rearwardly as indicated by an arrow 18 in FIG. 2.

Pivoting the steering and reversing member 4 in the opposite directionto a second deflecting position will cause its front section 4a to bemoved laterally outwardly from the neutral or non-deflecting positionshown in FIG. 1 while its rear section 4b is caused to be movedlaterally inwardly to a position in which its scoop-like jet deflectingmember is wholly or partly directly behind the discharge passage of thenozzle 3. Accordingly, a portion of the water jet will be intercepted bythe scoop-like member and deflected downwardly and forwardly in theabove-described manner.

FIG. 3 shows both steering and reversing members 4, 5 moved to thesecond deflecting or jet reversing position, namely with the rearsections 4b, 5b of both steering and reversing members positioneddirectly adjacent one another and aligned with the vertical center plane6. In this position, the two steering and reversing members receive thefull water jet and deflect it downwardly and straight forwardly to movethe water craft straight rearwardly.

The water jet is prevented from escaping laterally from the dischargepassage of the nozzle 3 by the front portions of the side panels 11,lateral extensions 20 and 21 of the top and bottom walls of the nozzle 3and curved front walls 22 and 23 which close off the space between thetop and bottom walls in the forward direction.

FIG. 4 shows the steering and reversing member 4 in the same position asin FIG. 1 and the other steering and reversing member 5 pivoted to aposition in which its rear section 5b is positioned directly adjacentand alongside the rear section 4b of the steering and reversing member4. With the two steering and reversing members in these positions, thefull water jet is first deflected laterally and then downwardly andforwardly at an angle to the vertical center plane 6 to propel the watercraft astern while turning it.

Naturally, the steering and reversing members 4 and 5 can be pivoted topositions intermediate the position shown in FIG. 1 on the one hand andthe side-steering and reversing positions shown in FIGS. 2 to 4, on theother hand.

Several modifications of the exemplary embodiment shown and describedabove can be made within the scope of the invention. For example, theside panels 11 of the steering and reversing members 4, 5 may have aconcavely curved vertical cross-section or contour, at least on theouter side, so as partially to contain the laterally deflected water jetin the side-steering forward propulsion mode illustrated in FIG. 2.

Moreover, the rear sections 4b, 5b of the steering and reversing members4, 5 may be shaped such that in the sidesteering reverse mode, the rearsections 4b, 5b of the steering and reversing members are partiallynested, the degree of nesting being dependent on the desired sharpnessof the turn.

The rear sections 4b, 5b of the steering and reversing members 4, 5 mayalso be modified to resemble Pelton wheel buckets and impart a smalleror larger degree of lateral deflection of the water jet in the reversemode.

I claim:
 1. A steering and reversing system for a marine jet propulsionunit having at a rear end thereof a stationary jet nozzle (3) whichdefines a rearwardly extending passage for discharging a water jetrearwardly from the unit,characterized in that the steering andreversing system comprises two elongate steering and reversing members(4, 5) which are positioned side by side and individually pivotable inopposite directions about upright axes (7, 8) from a non-deflectingposition to either of a first deflecting position and a seconddeflecting position, each steering and reversing member (4, 5) comprisesa generally upright side panel (11) and a top panel (12) which isgenerally perpendicular to the side panel and the rear portion of whichmerges with a downwardly and forwardly curved extension forming a jetreversing scoop, each steering and reversing member (4, 5) in thenon-deflecting position thereof forms a rearwardly directed extension ofthe nozzle passage and has its jet reversing scoop laterally offset fromthe region directly behind the nozzle passage, each steering andreversing member (4, 5) in the first deflecting position thereof has theforemost portion of its side panel (11) positioned relative to thenozzle passage and extending rearwardly and laterally outwardly todeflect a portion of the jet from the nozzle passage laterallyoutwardly, and each steering and reversing member (4, 5) in the seconddeflecting position thereof has its jet reversing scoop at least partlypositioned directly behind the nozzle passage to deflect a portion ofthe jet downwardly and forwardly.
 2. A steering and reversing system asclaimed in claim 1, characterized in that the steering and reversingmembers (4,5) are mounted for pivotal movement on vertical pivots (7)supported by the rear end of the nozzle (3) on opposite sides of avertical center plane (6) of the nozzle, the steering and reversingmembers (4,5) being shaped such that each of them is a mirror image ofthe other in the vertical center plane (6) .
 3. A steering and reversingsystem as claimed in claim 2, characterized in that each steering andreversing member (4,5) comprises a front section (4a,5a) and a rearsection (4b,5b) located respectively forwardly and rearwardly of thepivot axis (7), in that the side panel (11) extends over both the frontsection and the rear section, and in that the top panel (12) extendslaterally inwardly from the upper edge of the side panel (11).
 4. Asteering and reversing system as claimed in claim 3, characterized inthat the front and rear sections (4a,5a; (4b,5b) when viewed in planview include an obtuse angle and in that with both steering andreversing members (4,5) in the inactive position the rear sections(4b,15b) diverge rearwardly.
 5. A steering and reversing system asclaimed in claim 3 characterized in that the nozzle (3) is of asubstantially rectangular cross-section and comprises a horizontal upperwall (3a) and vertical side walls (3b,3c) associated with respectiveones of the steering and reversing members (4,5), in that each steeringand reversing member (4,5) in the non-deflecting position thereof hasthe said foremost portion of its side panel (11) generally aligned withthe associated nozzle side wall (3a,3b) and blocking a lateral openingprovided in the nozzle (3), in that the top panel (12) is substantiallyparallel with and positioned close to the upper horizontal nozzle wall(3a) at least at a region close to the associated pivot axis (7).
 6. Asteering and reversing system as claimed in claim 4 characterized inthat the two steering and reversing members (4,5) are pivotable to aposition in which their rear sections (4b,5b) are substantially parallelwith the facing edges of the top panels (12) positioned close to oneanother and in which the said foremost portions of the side walls (11)are aligned with or offset laterally outwardly from the respectiveassociated nozzle side walls (3b,3c) so that the rear sections of thesteering and reversing members (4,5) accommodate substantially all ofthe water jet and deflects it downwardly and forwardly.
 7. A steeringand reversing system as claimed in claim 6, characterized in that thenozzle (3) also includes a bottom wall and in that the top and bottomwalls of the nozzle (3) include a pair of extensions (20,21) whichextend laterally outwardly in opposite directions over the regions overwhich the front sections (4a,5a) of the steering and reversing members(4,5) are movable laterally outwardly from the nozzle sidewalls (3b,3c).8. A steering and reversing system as claimed in claim 7, characterizedin that a pair of front walls (22,23) extend laterally outwardly fromrespective ones of the nozzle side walls (3a,3b) at the front edges ofthe said lateral openings over the regions over which the front sections(4a,5a) of the steering and reversing members (4,5) are movablelaterally outwardly from the nozzle sidewalls (3b,3c) so that the frontwalls (22,23) close the gap between the extensions (20,21) over the saidregion.